Composition for forming etching stopper layer

ABSTRACT

An object of the present invention is to provide a composition for formation of etching stopper layer, which can simultaneously realize dry etching selectivity and low permittivity, and a production process of a semiconductor device using the same. This object can be attained by a composition for formation of etching stopper layer, comprising a silicon-containing polymer, the silicon-containing polymer contained in the composition comprising a disilylbenzene structure, and a production process of a semiconductor device comprising forming an etching stopper layer using the composition.

TECHNICAL FIELD

The present invention relates to a composition for the production of asemiconductor device, a production process of a semiconductor deviceusing the composition, and a semiconductor device produced using thecomposition. More particularly, the present invention relates to acomposition for formation of etching stopper layer for use in theformation of an etching stopper layer in the production of asemiconductor device by a damascene method, a production process of asemiconductor device using the composition, and a semiconductor deviceproduced using the composition.

BACKGROUND ART

In recent years, there are ever-increasing needs of integration insemiconductor devices, and the trend of the design rule is a steadilyincreasing integration density. This trend has led to a more complicatedsemiconductor device structure and, at the same time, a demand for anenhanced operating speed and reduced power consumption. To meet suchneeds, the adoption of a semiconductor device production process using adamascene method instead of the conventional semiconductor deviceproduction process has been proposed. In the damascene method, sincecopper can be used instead of aluminum used in the conventional wiringmaterial, an enhanced operating speed and reduced power consumption ofthe semiconductor device can be realized.

The damascene method is a method for manufacturing a semiconductordevice which comprises forming trenches or vias for wiring by etching orthe like in an insulating film provided on a substrate and filling awiring material such as copper into the trenches or vias. Damascenemethods may be classified into a single damascene method and a dualdamascene method according to the structure to be formed, or may beclassified into a trench first method and a via first method accordingto which of the trench and the via is formed first. In any method, sincevias or trenches are formed to a given depth by etching, an etchingstopper layer is provided for the restriction of the depth.

An example of pattern formation using the damascene method will bedescribed with reference to the accompanying drawings.

As shown in FIG. 1(a), an insulating film 101 is formed on a substrate(not shown) such as silicon. A wiring element 102 is formed on thisinsulating film, and an insulating film 103 is formed so as to cover thewiring element 102. Subsequently, an etching stopper layer 104 is formedon the insulating film 103 (FIG. 1(b)). An opening 105 as a connectionhole is then formed in the etching stopper layer, for example, bylithography (FIG. 1(c)). Further, an insulating layer 106 is formedthereon (FIG. 1(d)), and a via 107 and a trench 108 are then formed bydry etching (FIG. 1(e)). In this case, the insulating layer 106 locatedon the surface of the assembly is removed by etching. However, theetching rate of the etching stopper layer is so low that the underlyinginsulating layer 103 is not removed. The insulating layer 103 only inits part underlying the opening 105 is removed to form a via 107. Theinternal wall of the via and trench thus formed is if necessary coveredwith a barrier metal layer, a wiring material such as copper is thenfilled into the via and the trench, and the surface is polished bychemical mechanical polishing to form a plug (dual damascene method).

In this example, only one etching stopper layer is used. If necessary,however, after the insulating layer 106 is formed, one more etchingstopper layer may be formed thereon.

Regarding an insulting material used in the production of asemiconductor element by the damascene method, in order to lower thepermittivity of the semiconductor element, for example, organicmaterials and fluorosilicate glass have hitherto been used as a mainmaterial for constituting the element. The material used in the etchingstopper layer, however, should have a relatively higher level of etchingresistance than these insulating materials. That is, the ratio of therate of etching of the insulating material to the rate of etching of theetching stopper layer (known as selectivity) should be large. Despitesuch demands, the above organic materials and the like do not havesatisfactory etching resistance and thus do not provide a satisfactoryselectivity. Therefore, high-permittivity oxide films and nitride filmssuch as silicon oxide and silicon nitride films have hitherto been usedas a material for formation of etching stopper layer (for example,patent document 1 or patent document 2). Therefore, in the conventionalsemiconductor element, lowering in permittivity of the whole element wasdifficult.

Accordingly, a proposal has been made on a method in which thepermittivity of the whole semiconductor device is lowered by improvingthe structure of the semiconductor element (patent document 3). Thismethod, however, the production process per se should be changed, andthe conventional production process as such cannot be used withoutdifficulties.

-   Patent document 1: Japanese Patent Laid-Open Publication No.    102359/2001-   Patent document 2: Japanese Patent Laid-Open Publication No.    15295/2003-   Patent document 3: Japanese Patent Laid-Open Publication No.    349151/2000

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

Thus, any etching stopper layer, which can simultaneously realize highdry etching resistance and low permittivity, has not hitherto beenknown, and, in order to lower the permittivity of the wholesemiconductor device, the development of an etching stopper layer havinghigh dry etching resistance and low permittivity, or a composition forthe formation of the etching stopper layer has been desired.

Means For Solving the Problems

According to the present invention, there is provided a composition forformation of etching stopper layer, comprising a silicon-containingpolymer, characterized in that 5% to 100% by mole, based on the totalnumber of moles of silicon contained in the silicon-containing polymerin the composition, of silicon is contained in a disilylbenzenestructure.

Further, according to the present invention, there is provided asilicon-containing material for etching stopper formation or an etchingstopper layer produced by curing the above composition for formation ofetching stopper layer.

Furthermore, according to the present invention, there is provided aprocess for producing a semiconductor device, comprising the steps of:forming an insulating layer and an etching stopper layer on a substrate;removing part of the insulating layer by dry etching; and filling anelectrically conductive material into a groove or hole thus formed,wherein etching stopper layer is formed by curing the above compositionfor formation of etching stopper layer.

Effect of the Invention

The present invention provides a composition for the formation of anetching stopper layer to which a damascene method and the like areapplicable and which has low permittivity and has high dry etchingresistance under conditions for interlayer insulating film etching.

For the etching stopper layer formed using the composition according tothe present invention, the selectivity relative to various materials canbe varied by varying the etching gas used in etching. Specifically, whenetching of the etching stopper layer per se is contemplated, theselectivity relative to conventional hard mask materials such as SiO₂and SiN can be increased by properly selecting the etching gas.Alternatively, a method may be adopted in which the selectivity relativeto a material for the insulating layer, for example,methylsilsesquioxane, can be rendered close to 1 by selecting adifferent etching gas and the etching stopper layer and the insulatinglayer are simultaneously etched at the same etching rate. That is, theetching stopper layer formed using the composition according to thepresent invention can be utilized as an etching stopper layer and, atthe same time, can properly meet various requirements depending uponvarious semiconductor device production conditions.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a cross-sectional view illustrating a production process of asemiconductor device by a damascene method.

DESCRIPTION OF REFERENCE CHARACTERS

-   101 insulating film-   102 wiring element-   103 insulating film-   104 etching stopper layer-   105 opening-   106 insulating film-   107 via-   108 trench

BEST MODE FOR CARRYING OUT THE INVENTION

In the present invention, the composition for formation of etchingstopper layer comprises a silicon-containing polymer having adisilylbenzene ring. The disilylbenzene structure is a structurecomprising two silicon atoms attached to a benzene structure. A compoundor polymer having this structure is sometimes called “silylbenzene.”

The benzene ring constituting the disilylbenzene structure in theinvention of the present application may be part of a binuclear aromaticring. A preferred disilylbenzene structure is structure (I) representedby formula

wherein R¹ to R⁴ each independently are selected from a group consistingof hydrogen, an alkyl group, preferably a C₁ to C₃ alkyl group, analkenyl group, preferably a C₂ to C₄ alkenyl group, a cycloalkyl group,preferably a C₇ or C₈ cycloalkyl group, an aryl group, preferably a C₆to C₁₀ aryl group, an aralkyl group, preferably a C₇ to C₁₁ aralkylgroup, an alkylamino group, preferably a C₁ to C₃ alkylamino group, andan alkylsilyl group, preferably a C₁ to C₃ alkylsilyl group; and Arrepresents an aryl group, preferably a phenylene group.

In the present invention, a more preferred disilylbenzene structure isstructure (II) represented by formula

wherein R¹ to R⁴ are as defined in formula (I); and R⁵ to R⁸ areselected from a group consisting of hydrogen, a C₁ to C₃ alkyl group, ahalogen atom, a C₁ to C₃ alkoxide group, and a C₁ to C₃ amino group.

Among the silicon-containing polymers, silazane polymers or siloxazanepolymers having a disilylbenzene structure are preferred.

The above silicon-containing polymer may be produced by polymerizing anydesired monomer which can form a disilylbenzene structure in the polymerstructure. An example of a silicon-containing polymer production methodis to polymerize a monomer having a disilylbenzene structure. Suchmonomers are preferably monomers represented by formula (Ia) or morepreferably monomers represented by formula (IIa):

wherein R¹ to R⁸ are as defined in formula (II); and X's, which may bethe same or different, represent a halogen atom or a hydroxyl group.

Such monomers include 1,4-bis(dimethylchlorosilyl) benzene,1,4-bis(hydroxydimethylchlorosilyl)benzene, and1,4-bis(diethylchlorosilyl)benzene.

When the silicon-containing polymer used in the present invention issynthesized, two or more monomers described above may be mixed forpolymerization.

The monomer may be produced by any desired method. Specifically, themonomer may be produced, for example, by

-   (A) a Grignard reaction between a dihalogenated silane and an    aromatic Grignard reagent, or-   (B) a decarbonylation reaction between a diacyl aromatic compound    and a dihalogenated silane.

The composition according to the present invention indispensablycontains the above silicon-containing polymer having a disilylbenzenestructure. When the etching stopper layer is formed using thecomposition according to the present invention, in order to improve theprocessability of the etching stopper layer per se, the content ofcarbon in the silicon-containing polymer is preferably high. That is,the etching selectivity relative to an inorganic material used in a hardmask such as SiO₂ can be further increased by increasing the content ofcarbon in the silicon-containing polymer. To this end, the presence ofan aromatic group rather than an aliphatic hydrocarbon group as themonomer is preferred. The presence of a phenyl group is more preferred.Specifically, the silicon-containing polymer preferably has an aromaticgroup-containing structure in addition to the disilylbenzene structure.The content of carbon specifically varies, for example, upon propertiesrequired of the contemplated etching stopper layer and etchingconditions. In general, however, the carbon content is preferably notless than 30% by weight, more preferably not less than 55% by weight.

Further, the silicon-containing polymer used in the present inventionmay also be formed by using a combination of the above monomer having adisilylbenzene structure with other monomer. In particular, when themonomer having a disilylbenzene structure is less likely to undergohomopolymerization, the polymerization of a monomer for linking theabove monomer is effective. In this case, a polymer having asatisfactory degree of polymerization can be formed by copolymerizing abifunctional or trifunctional monomer with the monomer having adisilylbenzene structure. The bifunctional or trifunctional monomer maybe any desired one so far as it is polymerizable with the monomer havinga disilylbenzene structure and does not sacrifice the effect of thepresent invention. Specific examples of such monomers includehalogenated silanes such as phenyltrichlorosilane,diphenyldichlorosilane, methyltrichlorosilane, andmethylhydrodichlorosilane.

The silicon-containing polymer used in the present invention has adisilylbenzene structure, and the amount of the disilylbenzene structureshould be larger than a given amount.

Specifically, 5% to 100% by mole, preferably 20% to 60% by mole, basedon the total number of moles of silicon contained in thesilicon-containing polymer in the composition according to the presentinvention, of silicon should be contained in the disilylbenzenestructure in the silicon-containing polymer.

The number average molecular weight of the silicon-containing polymercontained in the composition according to the present invention ispreferably not less than 700, more preferably not less than 1000, fromthe viewpoint of maintaining film forming properties and is preferablynot more than 100,000, more preferably not more than 10,000, from theviewpoint of maintaining the composition in a viscosity range suitablefor handling.

Preferably not less than 10% by mole, more preferably not less than 30%by mole, of the monomers constituting the silicon-containing polymer isaccounted for by the monomer having a disilylbenzene structure, althoughthe content also varies depending upon, according to the presentinvention, the components contained in the composition, the mixing ratioof the components, and the type of monomers constituting thesilicon-containing polymer.

When the above requirements are satisfied, the composition may contain apolymer other than the above polymer having a disilylbenzene structure.

The composition for formation of etching stopper layer according to thepresent invention may contain a solvent and other additives in additionto the above polymer.

The composition according to the present invention generally contains asolvent in addition to the above polymer. A solvent which canhomogeneously dissolve or disperse the above polymer is selected as thissolvent. The polymer is selected from aromatic hydrocarbons, aliphatichydrocarbons and the like. Preferred are xylene, toluene, propyleneglycol monomethyl ether acetate, cyclohexane and the like.

The composition for formation of etching stopper layer according to thepresent invention may if necessary contain other additives. Suchadditives include crosslinking agents, specifically tetraethoxysilane,tetramethoxysilane and the like.

Upon heating, the composition for formation of etching stopper layeraccording to the present invention is cured and consequently isconverted to a silicon-containing material suitable for formation ofetching stopper layer. In general, the composition is coated onto a basematerial or the like, and the coating is heated on a hot plate or in aheating oven. In this case, the heating temperature is generally 250 to500° C., preferably 350 to 450° C., and the heating time is generally 10to 60 min, preferably 30 to 50 min. Heating conditions may varydepending upon the formulation of the composition and the type of thesilicon-containing monomer.

In the cured silicon-containing material prepared by heating the abovecomposition, in general, the polymer structure before curing remainssubstantially unchanged. Accordingly, 5% to 100% by mole, based on thetotal number of moles of silicon contained in the curedsilicon-containing material, of silicon is contained in thedisilylbenzene structure. This silicon-containing material ischaracterized by high dry etching resistance and low permittivity. Inparticular, the specific permittivity is lower than that of materialsused in the etching stopper layer in the prior art (about 8) and isgenerally not more than 3.5, particularly 2.8 to 3.2 and thus greatlycontributes to a reduction in permittivity of semiconductor devices.Therefore, the etching stopper layer according to the present inventionis a material that is very useful as an etching stopper layer insemiconductor devices.

The composition for formation of etching stopper layer according to thepresent invention is used for formation of etching stopper layer in asemiconductor device production process, particularly a damascenemethod. The semiconductor device production process using thecomposition for formation of etching stopper layer comprises the stepsof: forming an insulating layer and an etching stopper layer on asubstrate; removing part of the insulating layer by dry etching to forma groove or a hole; and filling an electrically conductive material intothe groove or hole. In this case, the etching stopper layer is formedusing the composition for formation of etching stopper layer.

In this production process, steps other than the step of forming theetching stopper layer may be carried out by using a combination of anyconventional methods. The production process of a semiconductor deviceaccording to the present invention is characterized by the step offorming an etching stopper layer using a composition containing asilicon-containing polymer having a disilylbenzene structure.

The method for formation of etching stopper layer comprises coating theabove composition for formation of etching stopper layer onto a surfaceof a substrate or an insulating layer or the like provided on thesubstrate and curing the coating.

The composition for formation of etching stopper layer may be coated byany method, for example, spin coating, dip coating, or curtain coating.Spin coating is preferred.

The composition coated onto the substrate is if necessary baked toremove excess solvent and is then heated for curing. The baking iscarried out at a temperature of about 100 to 250° C. for about 1 to 5min depending upon the solvent. Even when baking is carried out, heatingconditions for curing are the same as those described above.

Thus, the etching stopper layer formed using the composition forformation of etching stopper layer according to the present inventioncan realize excellent dry etching resistance and low permittivity. Forexample, the etching stopper layer has dry etching resistance favorablycomparable with silicon nitride or silicon oxide used as an etchingstopper layer in the prior art. Further, regarding the permittivity, itshould be noted that the specific permittivity of the conventionalsilicon nitride is about 8, whereas the specific permittivity of theetching stopper layer formed using the composition for formation ofetching stopper layer according to the present invention is about 3,demonstrating that the etching stopper layer formed using thecomposition for formation of etching stopper layer according to thepresent invention can realize a much lower permittivity than theconventional etching stopper layer.

COMPARATIVE SYNTHESIS EXAMPLE 1

The air in a 1-liter reaction vessel installed within a thermostaticchamber kept at a temperature of −5° C. was replaced by dry nitrogen.Dry pyridine (400 ml) was then placed in the reaction vessel. Thereaction vessel was held until dry pyridine reached a constanttemperature. Thereafter, phenyltrichlorosilane (PhSiCl3) (105.75 g) wasgradually added with stirring.

Next, after confirming that the contents of the reaction vessel reacheda constant temperature, 400 ml of hydrous pyridine containing 4.5 g ofdistilled water was gradually added over a period of about 30 min. Atthat time, a temperature rise was observed. After the completion of thereaction, when the reaction mixture reached a predetermined temperature,ammonia gas was blown into the reaction mixture.

After the completion of the reaction, the reaction mixture was stirredfor about one hr and was then filtered under pressure in a nitrogenatmosphere to give 750 ml of a filtrate.

Dry xylene (about 1000 ml) was added to this filtrate, and the solventwas removed under the reduced pressure to give 63 g of a solid polymer.The number average molecular weight of this polymer was measured by GPCand was found to be 900. The weight average molecular weight was 2600.This polymer was measured by FT-IR. As a result, absorption attributableto NH group was observed at wavenumber 3366 cm⁻¹; absorptionattributable to C—H in a benzene ring was observed at wavenumber around3000 cm⁻; absorption attributable to Si—O—Si was observed at wavenumberaround 1020 cm⁻¹; and

absorption attributable to Si—Ph was observed at wavenumber around 1400cm⁻.

Further, the results of ²⁹Si-NMR analysis using a tetramethylsilanestandard show that a signal of PhSiN₃ is observed at −31 ppm, a signalof PhSiN₂O is observed at −40 to −50 ppm, a signal of PhSiNO₂ isobserved at −55 to −65 ppm, and a signal of PhSiO₃ is observed at −70 to−80 ppm.

From the results of FT-IR and ²⁹Si-NMR, this comparative polymer A wasidentified to be a phenylsiloxazane polymer having on its main chain—(PhSiN3)—, —(PhSiN₂O)—, —(PhSiNO₂)—, and —(PhSiO₃)—. Further, it wasfound that this polymer A did not have a disilylbenzene structure.

SYNTHESIS EXAMPLE 1

Synthesis was carried out in the same manner as in Comparative SynthesisExample 1, except that 105.75 g of phenyltrichlorosilane (PhSiCI₃) and39.4 g of 1,4-bis(dimethylchlorosilyl)benzene were used as startingmaterials. As a result, about 63 g of a highly viscous polymer 1 wasobtained.

The molecular weight of this polymer 1 was measured. As a result, thenumber average molecular weight was 1500, and the weight averagemolecular weight was 4000.

FT-IR of this polymer 1 was measured. As a result, in addition toabsorptions observed in polymer A prepared in Comparative SynthesisExample 1, absorption attributable to adjacent hydrogen of a benzenering was observed around 780 cm⁻¹. The adjacent hydrogen of this benzenering is derived from 1,4-bis(dimethylchlorosilyl)benzene, that is, adisilylbenzene structure. This results of observation show that1,4-bis(dimethylchlorosilyl)benzene was introduced into polymer 1.Further, in polymer 1, the content of silicon in the disilylbenzenestructure was 37% by mole based on the total number of moles of siliconcontained in polymer 1.

SYNTHESIS EXAMPLE 2

The air in a reaction vessel installed within a thermostatic chamber wasreplaced by dry nitrogen. A solution of 47 g of phenyltrichlorosilane(PhSiCl₃), 56 g of diphenyldichlorosilane (Ph₂SiCl₂), 3.8 g ofmethyldichlorosilane (MeSiHCl₂), and 50 g of1,4-bis(dimethylchlorosilyl)benzene dissolved in 1000 ml of xylene wasthen introduced into the reaction vessel. Next, the internal temperatureof the reaction vessel was set to −5° C. When the temperature of thesolution reached a predetermined temperature, a mixed solution, composedof water and pyridine, prepared by dissolving 13 g of water in 1000 mlof pyridine, was introduced into the reaction vessel at a rate of about30 ml/min. In this case, upon the introduction of the mixed solution, areaction of halosilane with water took place, and, consequently, theinternal temperatuer of the vessel was raised to −2° C. After theintroduction of the mixed solution composed of water and pyridine wascompleted, the reaction mixture was stirred for one hr. Thereafter, inorder to fully react chlorosilane remaining unreacted, ammonia wasintroduced at a rate of 2 Nl/min for 30 min, and the reaction mixturewas stirred. Upon the introduction of ammonia, the formation of whiteprecipitate of ammonium chloride was observed. After the completion ofthe reaction, dry nitrogen was blown to remove ammonia remainingunreacted, and solvent displacement was then carried out under nitrogenpressure to give 100 g of polymer 2 which was clear and highly viscous.

The number average molecular weight of polymer 2 thus obtained was 2100.FT-IR of polymer 2 was measured. As a result, absorption attributable toNH group was observed around wavenumber 3350 cm⁻¹: absorptionattributable to Si—H was observed around 2160 cm⁻; absorptionattributable to Si—Ph was observed around 1140 cm⁻; absorptionattributable to C—H in a benzene ring was observed around 3000 cm⁻:absorption attributable to Si—O was observed at 1060 to 1100 cm⁻; and

absorption attributable to adjacent hydrogen of a benzene ring wasobserved at 780 cm⁻¹. In polymer 1, the content of silicon in thedisilylbenzene structure was 44% by mole based on the total number ofmoles of silicon contained in polymer 2. The content of carbon inpolymer 2 was 55% by weight.

SYNTHESIS EXAMPLE 3

Polymer 3 having a disilylbenzene structure was synthesized in the samemanner as in Synthesis Example 2, except that 66.3 g ofmethyltrichlorosilane was used instead of phenyltrichlorosilane anddiphenyldichlorosilane. In polymer 3, the content of silicon in thedisilylbenzene structure was 28.5% by mole based on the total number ofmoles of silicon contained in polymer 3. The content of carbon inpolymer 3 was 25% by weight.

EXAMPLE 1

Polymer A was adjusted in a xylene solvent to a predeterminedconcentration and was spin coated onto a silicon substrate. The coatingfilm was baked on a hot plate under conditions of 150° C./3 min and wasthen fired in the air under conditions of 400° C./30 min. Dry etchingproperties of the film thus obtained were evaluated using an etcher. Inthis case, in a damascene method, an interlayer insulation film wasetched. Gas G1 comprising C₄F₈/N₂/Ar at a mixing ratio of 5/10/100,which is a model gas in the case where processing is stopped at theetching stopper layer, was used as the gas. The total gas flow was 150SCCM. The evaluation was carried out using an etching apparatus (modelNE-N5000, manufactured by ULVAC, Inc.) under conditions of pressure 10Pa, temperature 20° C., antenna output 500 W, and bias output 250 W.

For each of polymer 1 and polymer 2, likewise, a xylene solution wasprepared, the xylene solution was spin coated, and the coating was firedunder conditions of 400° C./30 min to form a film. The films thusobtained were evaluated for dry etching properties in the same manner asin polymer A.

Further, methylsilsesquioxane (hereinafter referred to as “MSQ”) wasprovided as an example of a material used in a low-permittivityinterlayer insulation film, and silicon nitride (hereinafter referred toas “SiN”) and SiO₂ produced from tetraethoxysilane (hereinafter referredto as “TEOS-SiO₂”) were provided as an example of a material for theetching stopper layer and were evaluated in the same manner as describedabove.

The results were as shown in Table 1. TABLE 1 Table 1 Evaluation of dryetching properties (Low permittivity film etching conditions) Etchingrate Polymer (angstroms/min) Selectivity* Polymer A 5000 0.9 Polymer 1650 7.2 Polymer 2 510 9.2 MSQ 4670 — SiN 750 6.2 TEOS-SiO₂ 1190 3.9*Selectivity = (MSQ film etching rate)/(each film etching rate)

Comparison of the results for the films prepared from the above polymerswith the results for the MSQ film typical of the low-permittivityinterlayer insulation film shows that the films according to the presentinvention have a significantly low dry etching rate and excellent dryetching resistance. In particular, the etching rate ratio of the MSQfilm to the film formed from polymer 2, i.e., selectivity, reaches 9.2.

On the other hand, the selectivity of SiN and TEOS-SiO₂ which aretypical materials used as the etching stopper layer are 6.2 and 3.9,respectively. That is, it is apparent that, when a semiconductor deviceis produced by a damascene method using the composition for formation ofetching stopper layer according to the present invention, the etchingstopper layer according to the present invention has high dry etchingresistance and the selectivity relative to low-permittivity interlayerinsulation films such as MSQ is excellent.

The specific permittivity of the film formed from polymer 1 and thespecific permittivity of the film formed from polymer 2 were measuredand found to be 3.0 and 2.9, respectively. On the other hand, thespecific permittivity of SiN prepared by CVD is 8, indicating that thepermittivity of the film according to the present invention is very low.Thus, according to the present invention, the permittivity of theetching stopper layer can be lowered, that is, the effectivepermittivity of the semiconductor device can be lowered.

EXAMPLE 2

Dry etching properties of a film of polymer 2, a film of SiN and a filmof TEOS-SiO₂ were evaluated in the same manner as in Example 1, exceptthat, in a dual damascene method, SiN and SiO₂ were used as a hard mask,and gas G2 which is a model gas for stopping etching in these layers,that is, C₄F₈/O₂/Ar (mixing ratio=20/20/100) was used as gas. Theresults were as shown in Table 2. TABLE 2 Table 2 Evaluation of dryetching properties (Conditions for etching stopper layer removal)Etching rate Polymer (angstroms/min) Polymer 2 5420 SiN 420 TEOS-SiO₂590

Under the above gas conditions, the etching rate of the film formed formpolymer 2 is significantly different from the etching rate of SiN orSiO₂, and the selectivity is satisfactory. That is, the film formedusing the composition according to the present invention can beselectively removed using SiN or SiO₂ as a hard mask.

EXAMPLE 3

Dry etching properties of a film of polymer 2 and an MSQ film wereevaluated in the same manner as in Example 1, except that gas G3comprising C₄F₈/N₂/O₂/Ar at a mixing ratio of 5/10/10/200, which is amodel gas in the case where an MSQ film and an etching stopper layer aresimultaneously processed, was used as the gas. The results were as shownin Table 3. TABLE 3 Table 3 Dry etching properties (Conditions forremoval of interlayer insulation film and dry etching film) Etching ratePolymer (angstroms/min) Polymer 2 2550 MSQ 2730

The above results show that, under the above gas conditions, the etchingrate of the film formed from polymer 2 and the etching rate of the MSQfilm are similar to each other and thus can be simultaneously processed.

In general, it is difficult that, while the selectivity between theetching stopper layer and the MSQ layer is rendered close to 1, theselectivity between the etching stopper layer and SiN or SiO₂ isrendered large. Also from this point, it is apparent that thecomposition for formation of etching stopper layer according to thepresent invention is excellent.

EXAMPLE 4

For each of polymer 2 and polymer 3, a film was formed on a substrate inthe same manner as in Example 1. For comparison, an SiO₂ film and an SiNfilm (P—SiN) were provided.

For these films, the etching rate was measured in the same manner as inExample 1, except that the following gas was used.

-   G4: gas having a CHF₃/O₂/Ar mixing ratio of 20/20/100

G5: gas having a C₄H₈/N₂/Ar mixing ratio of 5/10/100 TABLE 4 Table 4Type of etching gas Type of film G4 G5 SiO2 4800 700 SiN 200 3400Polymer 3 800 1000 Polymer 2 50 3400Unit: angstroms/min

Comparison of the results for polymer 2 having a carbon content of 55%by weight with the results for polymer 3 having a carbon content of 25%by weight show that the film formed from polymer 2 having a high carboncontent exhibits an etching rate closer to that of the SiN film, whilethe selectivity between the film formed from polymer 2 and the SiO₂ filmis increased, demonstrating that the use of a suitable etching gas andthe use of a polymer having a high carbon content can render the etchingrate significantly larger than that of SiO₂ commonly used as a hardmask.

INDUSTRIAL APPLICABILITY

The present invention may be utilized, for example, in the formation ofan etching stopper layer in the production of semiconductor devices. Thesilicon-containing material for formation of etching stopper layer usingthe composition according to the present invention can realize excellentetching properties and low permittivity as an etching stopper layer.

1. A composition for formation of etching stopper layer, comprising asilicon-containing polymer, wherein 5% to 100% by mole, based on thetotal number of moles of silicon contained in the silicon-containingpolymer in the composition, of silicon is contained in a disilylbenzenestructure.
 2. The composition for formation of etching stopper layeraccording to claim 1, wherein said silicon-containing polymer has beenproduced by polymerizing a compound having a disilylbenzene structureand an aromatic group-containing compound.
 3. A silicon-containingmaterial for formation of etching stopper layer, comprising adisilylbenzene structure formed by curing a silicon-containing polymer,wherein 5% to 100% by mole, based on the total number of moles ofsilicon contained in the silicon-containing material, of silicon iscontained in a disilylbenzene structure.
 4. A semiconductor devicecomprising, as an etching stopper layer, a silicon-containing materialfor formation of etching stopper layer according to claim
 3. 5. Aprocess for producing a semiconductor device, comprising the steps of:forming an insulating layer and an etching stopper layer on a substrate;removing part of the insulating layer by dry etching; and filling anelectrically conductive material into a groove or hole thus formed,wherein said etching stopper layer is formed by curing a compositioncomprising a silicon-containing polymer, wherein 5% to 100% by mole,based on the total number of moles of silicon contained in thesilicon-containing polymer, of silicon is contained in a disilylbenzenestructure.
 6. The composition of claim 1, where the disilylbenzenestructure is represented by formula (I)

wherein R¹ to R⁴ each independently are selected from hydrogen, an alkylgroup, an alkenyl group, a cycloalkyl group, an aryl group, an aralkylgroup, an alkylamino group, and an alkylsilyl group, and Ar representsan aryl group.
 7. The composition of claim 1, where the disilylbenzenestructure is represented by formula (II)

wherein R¹ to R⁴ each independently are selected from hydrogen, an alkylgroup, an alkenyl group, a cycloalkyl group, an aryl group, an aralkylgroup, an alkylamino group, and an alkylsilyl group; and R⁵ to R⁸ areindependently selected from hydrogen, a C₁ to C₃ alkyl group, a halogenatom, a C₁ to C₃ alkoxide group, and a C₁ to C₃ amino group.
 8. Thecomposition of claim 1, where the polymer further comprises acomonomeric unit.
 9. The composition of claim 8, where the comonomericunit comprises an aromatic group.
 10. The composition of claim 8, wherethe comonomeric unit is derived from a monomer selected fromphenyltrichlorosilane, diphenyldichlorosilane, methyltrichlorosilane,and methylhydrodichlorosilane.
 11. The composition of claim 1, where thecomposition further comprises an additional polymer.
 12. The compositionof claim 2, where the compound having a disilylbenzene structure isrepresented by formula (Ia) or (IIa)

wherein R¹ to R⁴ each independently are selected from hydrogen, an alkylgroup, an alkenyl group, a cycloalkyl group, an aryl group, an aralkylgroup, an alkylamino group, and an alkylsilyl group, and Ar representsan aryl group; and R⁵ to R⁸ are independently selected from hydrogen, aC₁ to C₃ alkyl group, a halogen atom, a C₁ to C₃ alkoxide group, and aC₁ to C₃ amino group; and, X's, which may be same or different,represented by a halogen atom or a hydroxyl group.
 13. The compositionof claim 2, where the compound having the silylbenzene structure isselected from 1,4-bis(dimethylchlorosilyl) benzene,1,4-bis(hydroxydimethylchlorosilyl)benzene, and1,4-bis(diethylchlorosilyl)benzene.
 14. The composition of claim 2,where the aromatic group containing compound is selected fromphenyltrichlorosilane, diphenyldichlorosilane, methyltrichlorosilane,and methylhydrodichlorosilane.
 15. The silicon-containing material ofclaim 3, where the disilylbenzene structure is represented by formula(I)

wherein R¹ to R⁴ each independently are selected from hydrogen, an alkylgroup, an alkenyl group, a cycloalkyl group, an aryl group, an aralkylgroup, an alkylamino group, and an alkylsilyl group, and Ar representsan aryl group.
 16. The silicon-containing material of claim 3, where thedisilylbenzene is represented by formula (II),

wherein R¹ to R⁴ each independently are selected from hydrogen, an alkylgroup, an alkenyl group, a cycloalkyl group, an aryl group, an aralkylgroup, an alkylamino group, and an alkylsilyl group; and R⁵ to R⁸ areindependently selected from hydrogen, a C₁ to C₃ alkyl group, a halogenatom, a C₁ to C₃ alkoxide group, and a C₁ to C₃ amino group.
 17. Thesemiconductor device according to claim 4, where the disilylbenzenestructure is represented by formula (I)

wherein R¹ to R⁴ each independently are selected from hydrogen, an alkylgroup, an alkenyl group, a cycloalkyl group, an aryl group, an aralkylgroup, an alkylamino group, and an alkylsilyl group, and Ar representsan aryl group.
 18. The semiconductor device according to claim 4, wherethe disilylbenzene structure is represented by formula (II),

wherein R¹ to R⁴ each independently are selected from hydrogen, an alkylgroup, an alkenyl group, a cycloalkyl group, an aryl group, an aralkylgroup, an alkylamino group, and an alkylsilyl group; and R⁵ to R⁸ areindependently selected from hydrogen, a C₁ to C₃ alkyl group, a halogenatom, a C₁ to C₃ alkoxide group, and a C₁ to C₃ amino group.
 19. Theprocess of claim 5, where the disilylbenzene structure is represented byformula (I),

wherein R¹ to R⁴ each independently are selected from hydrogen, an alkylgroup, an alkenyl group, a cycloalkyl group, an aryl group, an aralkylgroup, an alkylamino group, and an alkylsilyl group, and Ar representsan aryl group.
 20. The process of claim 5, where the disilylbenzenestructure is represented by formula (II),

Wherein R¹ to R⁴ each independently are selected from hydrogen, an alkylgroup, a cycloalkyl group, an aryl group, an aralkyl group, analkylamino group, and an alkylsilyl group; and R⁵ to R⁸ areindependently selected from hydrogen, a C₁ to C₃ alkyl group, a halogenatom, a C₁ to C₃ alkoxide group, a C₁ to C₃ amino group.